DK151171B

DK151171B - TOBACCO SMOKE FILTER FOR A CIGARET

Info

Publication number: DK151171B
Application number: DK512177AA
Authority: DK
Inventors: Henry George Horsewell; John David Green; John Anthony Luke; Raymond John Harrison
Original assignee: British American Tobacco Co
Priority date: 1976-11-19
Filing date: 1977-11-18
Publication date: 1987-11-09
Also published as: AU3068677A; FI61618B; CA1078698A; DE2751559A1; FI773371A; NL7712335A; US4213470A; GB1585862A; DK151171C; BE860985A; CH620578A5; FI61618C; DK512177A; ZA776589B; DE2751559C2; AU509480B1

Description

i 151171in 151171

Opfindelsen angår et tobaksrøgfilter til en cigaret, af den i indledningen til krav 1 angivne art.The invention relates to a tobacco smoke filter for a cigarette, of the kind specified in the preamble of claim 1.

Det er opfindelsens formål at tilvejebringe et tobaksrøgfilter til en cigaret, af den i indledningen til krav 1 angivne art, som frembringer en forbedret fjernelse af flygtige, uønskede røgbestanddele, herunder carbonmonoxid og nitrogenmonoxid, samt en forbedret fjernelse af det totale, partikelformede materiale i røgen.It is an object of the invention to provide a tobacco smoke filter for a cigarette, of the kind set forth in the preamble of claim 1, which provides an improved removal of volatile, undesirable smoke components including carbon monoxide and nitrogen monoxide, and an improved removal of the total particulate matter in the smoke. .

Tobaksrøgfilteret ifølge opfindelsen er ejendommeligt ved det i den kendetegnende del af krav 1 angivne. Henvisningstallene i krav 1 og underkravene relaterer til den senere angivne fig. 1. Det har overraskende vist sig, at tobaksrøgfilteret ifølge opfindelsen giver anledning til en forbedret fjernelse af flygtige, uønskede røgbestanddele, herunder carbonmonoxid og nitrogenmonoxid, samt en forbedret fjernelse af det totale, partikelformede materiale i røgen.The tobacco smoke filter according to the invention is peculiar to that of the characterizing part of claim 1. The reference numerals of claim 1 and the subclaims relate to the FIG. 1. Surprisingly, it has been found that the tobacco smoke filter of the invention gives rise to improved removal of volatile undesirable smoke constituents, including carbon monoxide and nitrogen monoxide, as well as improved removal of the total particulate matter in the smoke.

Man kender ganske vist fra USA patentskrift nr. 3 768 489 et tobaksrøgfilter med skævt anordnede perifere noter, der skal frembringe en tværgående røgstrømning i filteret. I modsætning dertil er tobaksrøgfilteret ifølge opfindelsen beregnet til aksial røgstrømning. Den særlige tekniske virkning, som frembringes af tobaksfilteret ifølge opfindelsen, frembringes ikke af det kendte filter.It is admittedly known from US Patent No. 3,768,489 a tobacco smoke filter with skewed peripheral notes to produce a transverse smoke flow in the filter. In contrast, the tobacco smoke filter according to the invention is intended for axial smoke flow. The particular technical effect produced by the tobacco filter according to the invention is not produced by the known filter.

Man kender ganske vist også fra USA patentskrift nr. 2 954 773 et tobaksrøgfilter, der udviser en Venturi-passage, hvori røgen opnår en så høj hastighed, at tjærefjernelsen bliver meget effektiv på grund af den dynamiske påvirkning mellem røgen og filtertrådene. Selv om der i det kendte tobaksrøgfilter findes et ringformet rum, forekommer der ingen røgstrømning derigennem, og den særlige tekniske virkning, som frembringes af tobaksrøgfilteret ifølge opfindelsen, frembringes ikke af det kendte filter.It is also known from US Patent No. 2 954 773 a tobacco smoke filter which exhibits a Venturi passage in which the smoke achieves such a high speed that the tar removal becomes very effective due to the dynamic influence between the smoke and the filter wires. Although in the known tobacco smoke filter there is an annular space, there is no smoke flow through it and the particular technical effect produced by the tobacco smoke filter according to the invention is not produced by the known filter.

2 151171 I forbindelse med tobaksrøgfilteret ifølge opfindelsen er det en fordel, at de udvendige overflader af filterlegemet, der afgrænser det omtalte rum, i hovedsagen er uigennemtrængeligt for de partikelformede bestanddele af tobaksrøgen.In connection with the tobacco smoke filter according to the invention, it is advantageous that the outer surfaces of the filter body defining the space mentioned are substantially impervious to the particulate components of the tobacco smoke.

Omhyllingen omslutter med fordel filterlegemet fuldstændigt og afgrænser det nævnte rum eller de nævnte rum i hovedsagen over hele periferien af omhyllingen. Med fordel er filterlegemet i hovedsagen af cylindrisk form og er sammensat af et fibrøst materiale, der f.eks. kan udgøres af celluloseacetat. Det kan imidlertid være sammensat af et kornet materiale, f.eks. granuleret kul, eller af et opskummet materiale, eller en kombination af nogle af de i det foregående nævnte materialer, eller filterlegemet kan være udformet af et bundt af rør med fine boringer, f.eks. hule cellulose-acetatfibre.Advantageously, the enclosure completely encloses the filter body and defines said compartment or compartments substantially over the entire periphery of the enclosure. Advantageously, the filter body is generally cylindrical in shape and is composed of a fibrous material which e.g. may be cellulose acetate. However, it may be composed of a grainy material, e.g. granulated charcoal, or a foamed material, or a combination of some of the foregoing materials, or the filter body may be formed of a bundle of tubes with fine bores, e.g. hollow cellulose acetate fibers.

I et sådant filter er hele længden af filterlegemet tilgængeligt for filtrering af tobaksrøgen. Alligevel frembyder filteret ingen alvorlige problemer med hensyn til fremstilling og befæstelse til cigaretternes tobaksstænger. En normal profil kan opretholdes, og en normal produktionsproces kan anvendes.In such a filter, the entire length of the filter body is available for filtering the tobacco smoke. Still, the filter presents no serious problems with regard to the manufacture and attachment of the cigarette tobacco bars. A normal profile can be maintained and a normal production process can be used.

Med fordel er mellemsektionen i filterlegemet udformet ud i ét med en eller begge endesektioner.Advantageously, the intermediate section of the filter body is formed integrally with one or both end sections.

Hvis filterlegemet er fremstillet af celluloseacetat, kan den eller de ovenfor anførte udvendige overflade eller overflader gøres impermeable eller delvis impermeable ved varmepåvirkning af celluloseacetatet.If the filter body is made of cellulose acetate, the exterior surface (s) or surfaces listed above can be made impermeable or partially impermeable by heat acting on the cellulose acetate.

Opfindelsen skal i det følgende nærmere beskrives med henvisning til tegningen, hvor fig. 1 viser et cigaretfilter ifølge opfindelsen i aksial-snit, 3 151171 fig. 2 viser et tværsnit langs linien A-A* i fig. 1, fig. 3 viser et tværsnit langs linien B-B' i fig. 1, fig. 4 viser en anden udførelsesform for filteret ifølge opfindelsen i aksialsnit, fig. 5-6 skematisk viser alternative udførelsesformer for et filterlegeme svarende til det i figurerne 1-3 viste, fig. 7 og 8 viser henholdsvis et sidebillede og et tværsnit langs linien VIII-VIII i fig. 7, hvor der er vist en modificeret udførelsesform for filteret ifølge opfindelsen, og fig. 9 viser et aksialsnit gennem en anden udførelsesform for filteret ifølge opfindelsen.The invention will now be described in more detail with reference to the drawing, in which 1 shows a cigarette filter according to the invention in axial section, FIG. 2 shows a cross section along the line A-A * in FIG. 1, FIG. 3 shows a cross section along line B-B 'in FIG. 1, FIG. Figure 4 shows another embodiment of the filter according to the invention in axial section; 5-6 schematically illustrate alternative embodiments of a filter body similar to that shown in Figures 1-3; 7 and 8 show a side view and a cross section, respectively, along line VIII-VIII of FIG. 7, showing a modified embodiment of the filter according to the invention, and fig. 9 shows an axial section through another embodiment of the filter according to the invention.

Det i fig. 1-3 viste filter består af et filterlegeme i form af en 20 mm lang cylindrisk stang 1 af cellelulose-acetatfiltermateriale, der består af endesektioner la, lb med en diameter på 8 mm og ud i ét hermed en mellemliggende sektion 2, der er 10 mm lang og som har en diameter på 6 mm. Stangen 1 er omsluttet af en omhylling 3 af porøst papir.The FIG. 1 to 3 consist of a filter body in the form of a 20 mm long cylindrical rod 1 of cellulose acetate filter material consisting of end sections 1a, 1b having a diameter of 8 mm and integrally therewith an intermediate section 2 which is 10 mm long and having a diameter of 6 mm. The rod 1 is enclosed by a casing 3 of porous paper.

For at understøtte den del af omhyllingen 3, der strækker sig ind over sektionen 2, er der anordnet en kraftigere parpiromhylling 4, der ligger under omhyllingen 3. Omhyllingen 4 har tæt ved siden af hinanden anbragte perforeringer af større diameter, f.eks. 1,5 mm. Omhyllingen 4 kan eventuelt erstattes af en kraftigere, selvunderstøttende porøs omhylling 3. Omhyllingen 3 eller de to omhyllinger 3 og 4 kan være uigennemtrængelige for partikelformede bestanddele af tobaksrøgen.In order to support the portion of the casing 3 extending over the section 2, a more powerful parpiroma casing 4 located below the casing 3 is arranged. The casing 4 has closely adjacent perforations of larger diameter, e.g. 1.5 mm. Optionally, the casing 4 may be replaced by a more powerful, self-supporting porous casing 3. The casing 3 or the two casings 3 and 4 may be impermeable to particulate components of the tobacco smoke.

Filterlegemet 1 kan være udformet som en del af en stang af celluloseacetat, hvis længde andrager seks gange den tilsvarende længde af et enkelt legeme, og hvis diameter 4 151171 er 8 mm. Stangen underkastes en termisk formeproces på i langsgående retning med en vis afstand beliggende zoner (som beskrevet i patentansøgning nr. 1149/77), idet stangen derved i disse zoner reduceres til 6 mm i diameter. Denne proces kan resultere i en delvis aftætning af de respektive rundtgående overflader af sektionerne 2 med reduceret diameter, og i nærheden af disse overflader kan der ske en let komprimering af celluloseacetatfibrene. Stangen bliver derefter omviklet med omhyllingen 4 samt den porøse omhylling 3, og den således omviklede stang skæres herefter over vinkelret på aksen til dannelse af seks filtre.The filter body 1 may be formed as part of a bar of cellulose acetate, the length of which is six times the corresponding length of a single body and the diameter of which is 8 mm. The rod is subjected to a thermal molding process in longitudinally spaced zones (as described in patent application no. 1149/77), thereby reducing the rod in these zones to 6 mm in diameter. This process may result in partial sealing of the respective circumferential surfaces of the reduced diameter sections 2, and in the vicinity of these surfaces a slight compression of the cellulose acetate fibers may occur. The rod is then wrapped with the casing 4 as well as the porous casing 3, and the thus wrapped rod is then cut across perpendicular to the axis to form six filters.

Når filteret benyttes på en cigaret, passerer tobaksrøg gennem mellemsektionen af filteret, idet røgen i det mindste delvist strømmer gennem det ringformede rum 5, der danner en gennemstrømningspassage for røgen mellem omhyllingen 3 og den rundtgående overflade af sektionen 2, idet den alternative røggennemgang inde i selve celluloseacetaten har en betydeligt højere strømningsmodstand. Idet røgen passerer langs rummet 5, vil en stor del af de mere flygtige bestanddele af røgen, specielt carbonmonoxid og nitrogenmon-oxid, passere gennem understøtningsomhyllingen 4 og omhyllingen 3 og bliver derved fjernet fra røgen. Endvidere vil det trykfald, der dannes over omhyllingen 3, når røgen trækkes gennem filteret, få luft til at passere ind i rummet 5.When the filter is used on a cigarette, tobacco smoke passes through the middle section of the filter, the smoke flowing at least partially through the annular space 5, forming a flow passage for the smoke between the casing 3 and the circumferential surface of the section 2, the alternate smoke passage inside. the cellulose acetate itself has a significantly higher flow resistance. As the smoke passes along the space 5, a large portion of the more volatile constituents of the smoke, especially carbon monoxide and nitrogen monoxide, will pass through the support envelope 4 and the envelope 3, thereby being removed from the smoke. Further, the pressure drop formed over the casing 3 as the smoke is drawn through the filter will cause air to pass into the space 5.

Omhyllingen 3 kan være fremstillet enten af papir, der er af en vis porøsitet, eller af papir, der er blevet perforeret på kendt måde, f.eks. elektrostatisk, ved mekanisk gennem-brydning eller ved benyttelse af en laser. Den følgende tabel viser de reduktioner hvad angår mængden af carbonmonoxid og nitrogenmonoxid og den totale mængde partikelformede materiale, der opnås ved hjælp af det ovenfor beskrevne filter med omhyllinger af forskellige porøsiteter, men uden en understøttende omhylling 4. Det skal bemærkes, at nogle af de i tabellen viste udførelsesformer ligger 5 151171 udenfor opfindelsens omfang, jvf. den i krav 1 figurerende begrænsning hvad angår porøsiteten, og at disse udførelsesformer derfor skal opfattes som sammenligningseksempler.The envelope 3 may be made either of paper of a certain porosity or of paper which has been perforated in known manner, e.g. electrostatic, by mechanical breakthrough or by using a laser. The following table shows the reductions in the amount of carbon monoxide and nitrogen monoxide and the total amount of particulate matter obtained by the filter described above with envelopes of different porosities, but without a supporting envelope 4. It should be noted that some of the In the embodiments shown in the table, the invention is beyond the scope of the invention, cf. the limitation as to the porosity illustrated in claim 1, and that these embodiments must therefore be regarded as comparative examples.

% reduktion i røg porøsitet af papirom- carbon- nitrogen- total partikelhyl ling (W.T. enheder)x monoxid monoxid formet stofmængde naturlig porøsitet 1000 31 58 45 naturlig porøsitet 5000 56 75 53 elektrostatisk perforeret 1000 31 61 51 elektrostatisk perforeret 3000 64 67 75 elektrostatisk perforeret 10.000 87 92 87 W.T. enheder* er defineret ved en luftstrøm i cm^ pr. minut gennem 10 cm af papiret under et tryk på 10 cm vandsøjle, d.v.s.% reduction in smoke porosity of paper-carbon-nitrogen total particle coating (WT units) x monoxide monoxide shaped fabric amount of natural porosity 1000 31 58 45 natural porosity 5000 56 75 53 electrostatically perforated 1000 31 61 51 electrostatically perforated 3000 64 67 75 electrostatically perforated 10,000 87 92 87 WT units * is defined by an air flow in cm per minute through 10 cm of the paper under a pressure of 10 cm of water column, i.e.

cm^ min-1 10 cm-2 (10 cm vandsøjle)"1.cm ^ min-1 10 cm-2 (10 cm water column) "1.

Filtre, der svarer til de i fig. 1-3 viste, kan også fremstilles på en filterstangskombinationsmaskine ved at samle filterstænger af cylindriske sektioner af celluloseacetat.Filters similar to those in FIG. 1-3 can also be made on a filter bar combination machine by assembling filter bars of cylindrical sections of cellulose acetate.

Disse sektioner leveres fra en første stang på 8 mm diameter og en anden stang på 6 mm diameter. Sektioner, der er udskåret fra 8 mm og 6 mm stængerne, arrangeres ende til ende, idet de store og små diametersektioner er arrangeret skiftevis, hvorefter den således sammensatte stang omhylles i porøst papir 3, der består af en kombination af omhyllingerne 3 og 4. Den resulterende filterstang kan herefter afskæres i midten af hver af delene med den store diameter.These sections are supplied from a first rod of 8 mm diameter and a second rod of 6 mm diameter. Sections cut from the 8 mm and 6 mm bars are arranged end to end, the large and small diameter sections being arranged alternately, after which the rod thus composed is wrapped in porous paper 3 consisting of a combination of the casings 3 and 4. The resulting filter bar can then be cut into the center of each of the large diameter parts.

6 1511716 151171

Det cigaretfilter,, der er vist på fig. 4, består af et filterlegeme i form af en i hovedsagen cylindrisk stang 6 af celluloseacetat. Filterlegemet 6 omfatter en første, fuld diametersektion 7 og den anden del 8 med reduceret diameter, men er endvidere forsynet med et antal (på tegningen tre) rundtgående kamsektioner 9 med samme diameter som sektionen 7. Stangen 6 er indhyllet i et porøst papir 10, der er understøttet over den reducerede del 8 ved hjælp af kamsektionerne 9.The cigarette filter shown in FIG. 4, consists of a filter body in the form of a generally cylindrical rod 6 of cellulose acetate. The filter body 6 comprises a first, full diameter section 7 and the second section 8 of reduced diameter, but is further provided with a plurality (in the drawing three) of circumferential cam sections 9 of the same diameter as section 7. The rod 6 is shrouded in a porous paper 10. supported over the reduced portion 8 by the cam sections 9.

Delen 8 af legemet strækker sig til højre for den højre endesektion 9. Når filteret indsættes i en cigaret med den fulde diametersektion 7 stødende op til tobaksstangen på cigaretten, vil den endeoverflade af filteret, der vender bort fra tobakken, have et aftrappet udseende. Legemet 6 kan i sin højre ende have en yderligere fuld diametersektion svarende til sektionen 7.The portion 8 of the body extends to the right of the right end section 9. When the filter is inserted into a full diameter section 7 cigarette adjacent to the tobacco rod of the cigarette, the end surface of the filter facing away from the tobacco will have a stepped appearance. The body 6 may have at its right end an additional full diameter section corresponding to section 7.

Når filteret benyttes, passerer tobaksrøg i det mindste fortrinsvis gennem filteret gennem en røgpassage, der består af rummene 11, der er afgrænset af omhyllingen 10 og den rundtgående overflade af delen 8 på stangen 6. Selv om røgen ved successivt at passere gennem åbningerne 11 også strømmer gennem celluloseacetaten på de mellemliggende kamsektioner 9, har denne afbrudte strømningsvej stadigvæk en lavere strømningsmodstand end den alternative strømningsvej af samme længde helt inden for celluloseacetaten i legemet 8. Store mængder carbonmonoxid, nitrogenmonoxid og andre flygtige bestanddele fjernes fra røgen ved diffusion gennem de dele af omhyllingen 10, der afgrænser rummene 11. Endvidere indsuges luft i rummene 11 gennem disse dele af omhyllingen 10.When the filter is used, at least preferably tobacco smoke passes through the filter through a smoke passage consisting of the compartments 11 bounded by the casing 10 and the circumferential surface of the portion 8 of the bar 6. Although the smoke passes successively through the openings 11 as well. flowing through the cellulose acetate on the intermediate comb sections 9, this interrupted flow path still has a lower flow resistance than the alternate flow path of the same length completely within the cellulose acetate in the body 8. Large amounts of carbon monoxide, nitrogen monoxide and other volatile components are removed from the smoke by diffusion through the portions. the enclosure 10 defining the compartments 11. Furthermore, air is sucked into the compartments 11 through these parts of the enclosure 10.

Filterlegemet 6 kan være udformet ved hjælp af den beskrevne proces. Den rundtgående overflade af delen 8 med reduceret diameter kan derved blive delvis aftætnet.The filter body 6 may be formed by the process described. The circumferential surface of the reduced diameter portion 8 may thereby be partially sealed.

151171 7151171 7

Under benyttelse af de beskrevne filtre må det anses for givet, at en mindre del af de mere flygtige bestanddele af røgen passerer gennem sektionen med reduceret diameter og derved diffunderer gennem den delvis aftætnede rundtgåen-de overflade af denne sektion, hvorved der kan ske en delvis fjernelse via diffusion af sådanne bestanddele gennem omhyl-lingen 3 eller 10.Using the described filters, it should be considered that a smaller portion of the more volatile constituents of the smoke pass through the reduced diameter section, thereby diffusing through the partially sealed circumferential surface of this section, thereby allowing a partial removal via diffusion of such constituents through the casing 3 or 10.

Filtrene kan fæstnes til tobaksstængerne ved hjælp af særlige mundstykkepapirer, der ligesom omhyllingen 3 eller 10 skal være porøse således, at carbonmonoxid og nitrogenmonoxid kan diffundere gennem disse. Alternativt kan en fastgørelse finde sted ved hjælp af et snævert mundstykkebånd, og dette båndmateriale behøver ikke at være porøst.The filters can be attached to the tobacco rods by means of special nozzle papers which, like the casing 3 or 10, must be porous so that carbon monoxide and nitrogen monoxide can diffuse through them. Alternatively, attachment may take place by means of a narrow nozzle band, and this band material need not be porous.

Totallængden af filterlegemet 1 eller 6 kan være så kort som f.eks. 10 mm eller være så langt som f.eks. 45 mm. Længden af sektionen med reduceret diameter kan udvælges mellem 5 mm og 35 mm, og reduktionen i diameter kan udvælges mellem 1 mm og 7 mm.The total length of the filter body 1 or 6 may be as short as e.g. 10 mm or be as long as e.g. 45 mm. The length of the reduced diameter section can be selected between 5 mm and 35 mm and the reduction in diameter can be selected between 1 mm and 7 mm.

Konstruktionen og arrangementet af sådanne filtre kan varieres : I det viste udførelseseksempel i figurerne 1 - 3 er mellemsektionen 1 udført ud i ét med endesektionerne la og lb.The construction and arrangement of such filters can be varied: In the exemplary embodiment shown in Figures 1 - 3, the intermediate section 1 is integral with the end sections 1a and 1b.

Med den ovenfor beskrevne alternative fremstillingsmåde ved fremstilling af et tilsvarende filter er endesektionerne la og lb udført separat i forhold til sektionen 2, hvilket er vist skematisk i fig. 5. Enhver af sektionerne la og lb kan også være udformet ud i ét med sektionen 2, hvilket er vist for sektionens lb vedkommende i fig. 6.With the alternative method of preparation described above in producing a corresponding filter, the end sections 1a and 1b are made separately with respect to section 2, which is shown schematically in FIG. 5. Any of sections 1a and 1b may also be formed integrally with section 2, which is shown for section 1b in FIG. 6th

Sektionen af legemet ved opstrømsenden af delen med reduceret diameter kan være udformet til at fremme en foretrukken strømning af røgen til det rum eller de rum, fra hvilke s 151171 den udadgående diffusion af flygtige bestanddele finder sted. F.eks. kan som vist i fig. 7 og 8 sektionen la være forsynet med rundtgående og i langsgående retning med afstand beliggende noter 12. I stedet for som vist at afsluttes før enden af tobaksstangen 13 kan tilsvarende noter strække sig i sektionens la fulde længde.The section of the body at the upstream end of the reduced diameter portion may be configured to promote a preferred flow of the smoke to the room or rooms from which the outward diffusion of volatiles takes place. Eg. as shown in FIG. 7 and 8 section 1a is provided with circumferential and longitudinal spaced notes 12. Instead of being terminated before the end of the tobacco bar 13, corresponding notes may extend in the full length of section 1a.

I stedet for eller som supplement til sådanne noter kan en hulhed eller hulheder arrangeres med kegleformet opbygning imod enden af sektionen la i den ende, der vender bort fra tobakken. Overfladen eller overfladerne af en sådan hulhed eller not kan aftætnes således, at disse overflader i det store og hele bliver røgimpermeable.Instead of or in addition to such notes, a cavity or cavities may be arranged with cone-shaped structure towards the end of section 1a at the end facing away from the tobacco. The surface or surfaces of such a cavity or groove can be sealed so that these surfaces are largely smoke impermeable.

Rummet 5 eller rummene 11, der er afgrænset af mellemsektionen af legemet, kan f.eks. indeholde aktivt kul, der bidrager til en fjernelse af bestanddele af røgen.The compartment 5 or compartments 11 bounded by the intermediate section of the body may e.g. contain activated charcoal which contributes to the removal of constituents of the smoke.

De filtre, der er beskrevet ovenfor, kan være kombineret enten ud i ét eller separat med en filtersektion, der er forsynet med en røgaccelererende indsnævnring i sit tværsnit, hvilket arrangement er beskrevet i patentansøgning nr. 4410/77.The filters described above may be combined either in one or separately with a filter section provided with a smoke accelerating constriction in its cross section, the arrangement of which is described in patent application No. 4410/77.

F.eks. kan der anordnes en noget længere sektion la, som vist i fig. 9, hvilken sektion er forsynet med en ringformet not 14, der er udfyldt eller belagt med et tætningsmateriale 15 til dannelse af en røgaccelererende åbning 16 i opstrømsenden af den tilbageblevne del af denne sektion og sektionerne 2 og lb.Eg. a slightly longer section 1a can be arranged, as shown in FIG. 9, which section is provided with an annular groove 14 which is filled or coated with a sealing material 15 to form a smoke accelerating opening 16 at the upstream end of the remaining portion of this section and sections 2 and 1b.

I det i fig. 4 viste filter kan man i stedet for at benytte de rundtgående kamme 9 på stangen 6 til understøtning af omhyllingen 10 benytte delen 8 med reduceret diameter til dette formål, hvilken del kan være forsynet med langsgående udragende kamme således, at der dannes et antal parallelle røgpassager.In the embodiment of FIG. 4, instead of using the circumferential ridges 9 on the rod 6 to support the casing 10, the reduced diameter portion 8 can be used for this purpose, which portion may be provided with longitudinal protruding ridges to form a plurality of parallel smoke passages. .

Claims

The reduced diameter portions 2 or 8 of any of the above-described embodiments may be provided with other cross sections, e.g. triangular or polygonal. Patent claim:%

A tobacco smoke filter for a cigarette, said filter having a filter body (1) comprising at least one intermediate section (2) existing between end sections (1a, 1b), each of said sections being made of a filter material, and a porous casing (3) of sheet-shaped material permeable to volatile constituents in the tobacco, characterized in that the intermediate section (2) has a cross section smaller than the end sections (1a, 1b) and fully within the end sections (la, lb) contour lines, seen in the axial direction of the tobacco smoke filter, that the porous casing (3) of sheet-shaped material along with the intermediate section (2) defines at least one space (5) providing a path through which smoke can pass when the filter is in use and from which certain components can be removed from the smoke by diffusion through the casing (3), the casing (3) having a porosity of at least 3000 WT means that it completely encloses the filter body (1), that it follows the boundaries of the room (s) (5) along most of the casing (3), and that it does not extend beyond the periphery of the cigarette to which it is intended; attached.

Filter according to claim 1, characterized in that the filter body (1) is substantially cylindrical in shape.

Filter according to claims 1-2, characterized in that the felt body (1) is made of cellulose acetate. 151171 ίο

Filter according to claims 1-3, characterized in that the body (1) has an intermediate section (2) defining a single elongated annular space (5).

Filter according to claims 1-4, characterized in that the intermediate section (2) is provided with a plurality of annular cam sections separating a plurality of annular compartments (5).

Filter according to claims 1-5, characterized in that the intermediate section (2) is formed integrally with at least one end section (1a, 1b).

Filter according to claims 1-6, characterized in that the end section (1a), which during use of the filter on a smoking article is up to the tobacco string, is provided with grooves and / or cavities for mainly controlling the smoke into the room or rooms ( 5).

Filter according to claims 1-7, characterized in that said end section (1a) is formed with a smoke accelerating constriction or opening.